Polyethylene polyamines are widely known and have general utility as corrosion inhibitors in coolants and lubricant formulations and have utility as coagulants or flocculants for the agglomeration of suspended solids from liquid solutions or slurries. They also have utility in formulating plasticizers and antioxidants for polymers. The linear, as opposed to the cyclic, polythylene polyamines have greater utility for these applications and examples of such linear polyethylene polyamines including diethylenetriamine, triethylenetetramine, tetraethylenepentamine and pentaethylenehexamine.
There have been two standard routes to the preparation of polyethylene polyamines, one being through the chloride route wherein ethylene dichloride is reacted with ammonia or a diamine to produce the polyethylene polyamine and the second has been through the reaction of ethanolamine and ethylenediamine. One of the major disadvantages of the chloride process is that it involves the use of a corrosive halogen-containing starting material. A byproduct of the process is that it generates corrosive hydrochloric acid, vinyl chloride and toxic mustards in the process.
The following patents are representative of processes involving the preparation of polyethylene polyamines from ethanolamine and ethylenediamine.
U.S. Pat. Nos. 4,036,881; 4,394,524; and 4,503,253 show the use of various phosphorus containing catalysts such as phosphoric acid on silica and rare earth metal hydrogen phosphates such as lanthanum hydrogen phosphate.
U.S. Pat. No. 4,316,841 shows the manufacture of polyethylene polyamines through reforming of polyethylene polyamines using a phosphorus catalyst.
U.S. Pat. No. 4,314,083 shows the utilization of the salt of nitrogen or sulfur containing substance as a catalyst.
U.S. Pat. No. 4,362,886 shows the use of arsenic, antimony, or bismuth as a catalyst. p U.S. Pat. No. 4,399,308 shows the use of a Lewis acid halide for preparing polyethylene polyamines.
U.S. Pat. No. 2,364,278 and South African Pat. No. 785,635 disclose processes for the manufacture of polyethylene polyamines by reacting 2-aminoethyl sulfuric acid with ammonia or amine in the presence of alkali metal hydroxide.